Add back the secrets_store action into mapping.json
Add back the secrets_store action into mapping.json

This action is not included in the mapping.json and it is required
to retrieve secrets from barbican in the workflows

Change-Id: I68f2a75a30cbafba1dc5cc2ca222483c7b92dca1
Closes-Bug: #1800820

openstack/mistral,openstack/mistral